To address the shortfall in M&S software capabilities for modeling radomes of various types, PEO-DD(X)/PMS-500 commissioned the development of a plan to satisfy these needs. FSS M&S was identified as one of the most promising FSS simulation approaches, and was selected for further development. This report presents a summary of the verification and validation of the enhanced FSS M&S code over a wide range of electromagnetic test cases, including infinite and finite structures. The verification and validation of FSS M&S conducted under this study was extensive, and can be considered a significant success. Of the 16 cases investigated, 9 cases have numerical and measured results for comparison. Each test case considered in this V&V effort was selected to verify the performance of FSS M&S for a specific application or to validate the underlying theoretical framework of the M&S package. No example studied produced less than favorable results. Throughout this study, FSS M&S demonstrated that it can accurately predict the performance of a wide range of radome structures. Based on the reported results, FSS M&S has been verified and validated as a capable FSS radome modeling and simulation tool for use within the DD(X) program.